Calculate Air Speed in Turbine Tunnel - PSF.AT.00252V2

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Discussion Overview

The discussion revolves around calculating the speed of air flowing through an orifice, specifically using volumetric flow rate and cross-sectional area. Participants are exploring the necessary formulas and parameters needed for this calculation.

Discussion Character

  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant notes that cubic feet per minute (cfm) is a unit of volumetric flow, not speed, and suggests dividing the flow rate by the cross-sectional area to find velocity.
  • Another participant questions the initial post for lacking necessary information, such as upstream pressure or mass flow, to provide a meaningful answer.
  • A later reply provides specific values for air volume, orifice area, and air pressure, indicating a desire to calculate the velocity of air.
  • One participant prompts the original poster to consider the units involved in the calculation to determine the necessary operations for finding velocity.
  • Another participant expresses confusion about the provided numbers, suggesting they may be unusual or incorrect.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are multiple viewpoints regarding the necessary information and calculations needed to determine air speed. Some express confusion about the data provided.

Contextual Notes

Participants highlight missing assumptions, such as the need for upstream pressure or mass flow, which may affect the calculation. There is also a focus on ensuring the correct interpretation of units in the context of the problem.

albertwinnie
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Newbie here;I have a project where I need to know the formula to find the speed of a known quantity of air in cubic feet per minute going though an orfice.So I can calculate
psf.at.00252v2
 
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Firstly, [tex]ft^3/min[/tex] is not a unit of speed, rather of volumetric flow, typically denoted by the variable, Q. Dividing Q by the cross-sectional area will give you the velocity.

However, aside from that, you've given us nothing. You are posting zero knows in this problem and expect an answer for something. Do you have upstream pressure? Mass flow? What?
 
Thank you for that Minger,,,,,I,m off to the hospital for a scat scan and will post more details when I return.
 
Hi Minger,,,,OK,Back in home,,

air volume=375,000 cfm3

orfice=18,900 ft2

air pressure=20 inches water column

velocity of air = ?
 
Look at the units.

You have flow in
[tex]\frac {ft^3} {min}[/tex]

and an area in
[tex]ft^2[/tex]

can you look at that and figure out the operation needed to arrive at a number in

[tex]\frac {ft} {min}[/tex] ?
 
What am I missing ?
 

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